The present invention is directed to gas fired burners. In particular, the present invention is directed to gas fired burners of the type which may be used in industrial furnaces and the like.
U.S. Pat. No. 5,993,193 (Loftus et al.) discloses a gas fired burner for use in applications such as chemical process furnaces for process heaters in refineries and chemical plants. The burner is provided with a plurality of fuel gas inlets for enabling manipulation of the flame shape and combustion characteristics of the burner based upon variation in the distribution of fuel gas between the various fuel gas inlets. This invention is directed to varying the pattern of heat flux being produced when the burner apparatus is in operation. However, the invention here is directed to a circular burner with intricate design aimed at achieving a great degree of premixing and reduced NOx emissions. More importantly, the heat flux pattern here is the longitudinal heat flux distribution along the flame. This disclosure does not teach heat flux distribution across the burner opening, perpendicular to the flow of flue gas immediately outside the burner opening.
U.S. Pat. No. 5,295,820 (Bicik et al.) teaches a linear burner with jets extending through an opening made in a wall of a body of the burner defining an air-distribution chamber. The jets are connected to a series of tubes for supplying fuel gas or a gas/air mixture with the tubes passing through the body of the burner in order to be connected on the outside to a distribution housing provided with gas or with a gas/air mixture. The housing has a means to selectively supply the tubes joined to the jets. The intent here is to have a burner with a wide range of heating power, or turndown ratio. However, this invention does not teach a single air supply, single fuel supply, and single burner control system so as to simplify the design and reduce costs while achieving an object of a desired heat release profile dictated by process requirements.
Additionally, there are arrangements of a multitude of burners in furnaces that achieve a uniform heat flux at a given elevation and a given heat flux profile along the elevation, such as in a side-fired reformer or a terraced-wall reformer, generally known in the art. However, these burners are individually controlled. They do not share a common fuel supply manifold or a common air supply manifold. As burners, they are not able to deliver specified heat flux profiles in two dimensions simultaneously. In addition, their cost is usually very high because of the need for individual controls.
It would be desirable to have a burner design that would meet specified heat flux profiles in two dimensions (e.g., longitudinal and transverse dimensions) simultaneously. It would also be desirable for the above to be achieved while meeting safety, flame stability, and low-cost requirements.